service a/c light

1993 BUICK RIVIERA
90,000 MILES • 6 CYL • FWD • AUTOMATIC
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CMFC_77
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the service a/c light is on in my wife’s car, 1993 Buick Riviera. i check all the fuses only found the cigarette one bad, changed it, did not fix the a/c i checked the power at the compressor and i do not have any power. i put a set of gages on it without the car running both sides showed about 75-80 pounds, any help would be Appreciated

thanks
calvin
Apr 7, 2011 at 4:33 PM
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WRENCHTECH
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The control module has shut the system down because it has recognized a problem, usually fast cycling that is sometimes cause by low refrigerant. You can reset the module temporarily by disconnecting the battery for testing purposes but don't try to continue to use it that way. It shut itself down to prevent damage.
Apr 7, 2011 at 5:15 PM
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CMFC_77
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thank you i will try that tonight, what should the pressure be when it is running?
Apr 7, 2011 at 5:41 PM
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WRENCHTECH
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There are many, many variables involving the pressures. You really need to understand how A/C works to recognize what's correct and what isn't. With outside temp over 70degrees and on high blower, you should be seeing something between 30 and 40 on the low side and 175 to 250 on the high side but that's not a rule by any means. The best thing to do is have it completely evacuated and recharged with the exact charge it should have. That is the ONLY way to ever know if it has the right charge in it or not.
Apr 7, 2011 at 5:48 PM
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CMFC_77
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thank you for the info
Apr 7, 2011 at 6:06 PM
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CMFC_77
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by disconnecting the battery it reset the system. I thought by fixing the vacuum hoses that were leaking would fix the problem but it has not. The car is running better but still having problems with the service a/c light coming one.
May 4, 2011 at 1:25 PM
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WRENCHTECH
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And what did the shop determine when you brought it to them to have the codes scanned and the system diagnosed?
May 4, 2011 at 1:29 PM
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CMFC_77
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have not had the money to take it to a shop yet.
May 4, 2011 at 3:22 PM
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WRENCHTECH
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That is your next step so let us know when you do.
May 4, 2011 at 3:30 PM
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CMFC_77
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will do thanks for the help.
May 4, 2011 at 6:24 PM